Scroll compressor

ABSTRACT

A scroll compressor ( 10 ) includes a bearing oil supply passage ( 70 ) configured to supply a refrigeration oil from an oil reservoir ( 18 ) located in a casing ( 15 ) to a bearing of a driving shaft ( 60 ). An oil groove ( 80 ) which communicates only with the oil reservoir ( 18 ) in the casing ( 15 ) through a connection passage ( 86 ) and a capillary tube ( 87 ) is formed on a thrust sliding surface ( 35 ) of a fixed scroll ( 30 ). Since the bearing oil supply passage ( 70 ) is not in communication with the oil groove ( 80 ), even when an orbiting scroll ( 40 ) is tilted and a pressure of the oil groove ( 80 ) decreases, a pressure of the bearing oil supply passage ( 70 ) does not decrease, and accordingly, the refrigeration oil is supplied from the bearing oil supply passage ( 70 ) to the bearing of the driving shaft ( 60 ).

TECHNICAL FIELD

The present disclosure relates to measures to improve reliability ofscroll compressors.

BACKGROUND ART

Conventionally, scroll compressors have been widely used to compress,e.g., refrigerants or air. For example, Patent Document 1 discloses ahermetic scroll compressor. Here, the structure of the scroll compressor(500) disclosed in Patent Document 1 is described with reference to FIG.9.

The scroll compressor (500) includes a vertically oriented cylindricalcasing (510) in which a compression mechanism (520) and a motor (515)are housed. The compression mechanism (520) is disposed above the motor(515), and a driving shaft (550) connects the compression mechanism(520) to the motor (515).

The compression mechanism (520) includes a fixed scroll (525), anorbiting scroll (530), and housing (540). The orbiting scroll (530) hasan end plate (531), a lap (532) projecting from the front side of theend plate (531), and a cylindrical portion (533) projecting from thebackside of the end plate (531). In the compression mechanism (520), thelap (532) of the orbiting scroll (530) is engaged with a lap (526) ofthe fixed scroll (525), thereby forming compression chambers (521). Theend plate (531) of the orbiting scroll (530) has a thrust slidingsurface (536) which is in sliding contact with a thrust sliding surface(527) of the fixed scroll (525). The driving shaft (550) has aneccentric portion (551) inserted in the cylindrical portion (533) of theorbiting scroll (530). When the driving shaft (550) rotates, theorbiting scroll (530) performs orbital motion and a refrigerant suckedin the compression chambers (521) is compressed,

In the scroll compressor (500), the driving shaft (550) includes an oilsupply passage (555) formed therein. A lubricating oil having flowedfrom a bottom portion of the casing (510) into the oil supply passage(555) is supplied to a bearing portion through a first branch passage(556) and a second branch passage (557). Part of the lubricating oilflowing through the oil supply passage (555) comes out of a terminal endof the oil supply passage (555) which opens at an upper end of theeccentric portion (551).

The pressure of the refrigerant present in the compression chambers(521) acts on the front side of the end plate (531) of the orbitingscroll (530). Accordingly, an increase in the pressure of therefrigerant in the compression chambers (521) causes the orbiting scroll(530) to be pushed down, and thereby reduces air tightness of thecompression chambers (521).

On the other hand, the scroll compressor (500) includes a seal ring(541) provided between the housing (540) and the orbiting scroll (530).The pressure present inside the seal ring (541) is substantially equalto the pressure of the lubricating oil having flowed out from theterminal end of the oil supply passage (555) (consequently,substantially equal to the pressure of the refrigerant discharged fromthe compression mechanism (520)). Accordingly, the orbiting scroll (530)is upwardly pushed by the pressure acting on the backside of the endplate (531). The orbiting scroll (530) is consequently pressed againstthe fixed scroll (525), and the air tightness of the compressionchambers (521) is ensured.

However, the force pressing the orbiting scroll (530) against the fixedscroll (525) sometimes becomes too strong. In such a case, the frictionforce generated between the thrust sliding surface (536) of the orbitingscroll (530) and the thrust sliding surface (527) of the fixed scroll(525) becomes strong, resulting in an increase in power consumption ofthe motor (515).

On the other hand, the scroll compressor (500) includes an oil groove(534) and a communication passage (535) which are formed on the endplate (531) of the orbiting scroll (530). The oil groove (534) is agroove which opens on the thrust sliding surface (536) of the end plate(531) and surrounds the lap (532).

The oil groove (534) communicates with the inner space of thecylindrical portion (533) through the communication passage (535).Accordingly, the pressure inside the oil groove (534) is substantiallyequal to the pressure of the lubricating oil having flowed out from theterminal end of the oil supply passage (555). The pressure of thecompression chamber (521) adjacent to the oil groove (534) isapproximate to the pressure of the low-pressure refrigerant sucked inthe compression chamber (521) and lower than the pressure of the oilgroove (534). Accordingly, a pressure difference between the oil groove(534) and the compression chamber (521) causes a sufficient amount ofthe lubricating oil to be supplied to the thrust sliding surfaces (527,536). Consequently, the friction force between the thrust slidingsurface (536) of the orbiting scroll (530) and the thrust slidingsurface (527) of the fixed scroll (525) becomes weak, and accordingly,the power consumption of the motor (515) is kept low.

CITATION LIST Patent Document

PATENT DOCUMENT 1: Japanese Patent No. 3731068

SUMMARY OF THE INVENTION Technical Problem

In the orbiting scroll (530) of the scroll compressor (500), theinternal pressure of the compression chambers (521) acts on the lap(532) projecting from the front side of the end plate (531), and a loadfrom the driving shaft (550) acts on the cylindrical portion (533)projecting from the backside of the end plate (531). The line of actionof the gas pressure acting on the lap (532) and the line of action ofthe load acting on the cylindrical portion (533) intersect the axialdirection of the orbiting scroll (530) at right angles but do notintersect each other. Accordingly, a moment acts on the orbiting scroll(530) in a direction tilting the orbiting scroll (530).

If the pressure acting on the backside of the end plate (531)(specifically, the pressure inside the seal ring (541)) is sufficientlyhigh, the orbiting scroll (530) is strongly pressed against the fixedscroll (525), and accordingly, the orbiting scroll (530) is not tiltedeven by the moment acting thereon. However, in an operational statewhere the pressure acting on the backside of the end plate (531) isinsufficiently high (for example, in an operational state where thepressure of the refrigerant discharged from the compression mechanism(520) is very low), the orbiting scroll (530) is sometimes tilted,resulting in an increase in the clearance between the thrust slidingsurface (536) of the orbiting scroll (530) and the thrust slidingsurface (527) of the fixed scroll (525). In the scroll compressor (500)shown in FIG. 9, the increase in the clearance between the thrustsliding surfaces (527, 536) may disadvantageously cause the pressure inthe oil groove (534) to drop abruptly.

In the conventional scroll compressor (500) shown in FIG. 9, the oilgroove (534) communicates with the bearing portion of the compressionmechanism (520) through the communication passage (535) and the oilsupply passage (555). Therefore, when the orbiting scroll (530) istilted and the pressure in the oil groove (534) abruptly drops, thepressure of the oil supply passage (555) communicating with the oilgroove (534) decreases, and accordingly, the lubricating oil maydisadvantageously flow backward from the bearing portion to the oilsupply passage (555) through the branch passages (556, 557). Thisback-flow of the lubricating oil from the bearing portion to the oilsupply passage (555) may cause a shortage of lubrication in the bearingportion and troubles such as seizure.

It is therefore an object of the present disclosure to improvereliability of scroll compressors.

Solution to the Problem

A first aspect of the present disclosure relates to a scroll compressorincluding: a casing (15); a compression mechanism (20) housed in thecasing (15) and including a fixed scroll (30) and an orbiting scroll(40); and a driving shaft (60) housed in the casing (15) and engagedwith the orbiting scroll (40), in which the compression mechanism (20)is configured to discharge a compressed fluid into the casing (15) andto generate a pressing force which presses the orbiting scroll (40)against the fixed scroll (30). According to the first aspect, an endplate (41) of the orbiting scroll (40) and the fixed scroll (30)respectively include a thrust sliding surface (45) and a thrust slidingsurface (35) which are in sliding contact with each other, the thrustsliding surface (45) of the orbiting scroll (40) or the thrust slidingsurface (35) of the fixed scroll (30) includes an oil groove (80) intowhich a lubricating oil flows, and the scroll compressor is providedwith a bearing oil supply passage (70) which is not in communicationwith the oil groove (80) and is configured to supply the lubricating oilin an oil reservoir (18) located in the casing (15) to a bearingprovided in the compression mechanism (20) for the driving shaft (60),and a groove communication passage (85) which connects the oil groove(80) to the oil reservoir (18) in the casing (15).

According to the first aspect of the present disclosure, when thedriving shaft (60) drives the orbiting scroll (40), the fluid is suckedinto the compression mechanism (20) to be compressed therein. Thecompression mechanism (20) then discharges the compressed fluid into thecasing (15). Accordingly, the lubricating oil stored in the casing (15)has a pressure which is substantially equal to a pressure of the fluiddischarged from the compression mechanism (20). The lubricating oil inthe casing (15) passes through the bearing oil supply passage (70) to besupplied to the bearing in the compression mechanism (20).

In the compression mechanism (20) of the first aspect, the orbitingscroll (40) is pressed against the fixed scroll (30) in order to ensureair tightness of compression chambers. Further, the thrust slidingsurface (45) of the orbiting scroll (40) slides on the thrust slidingsurface (35) of the fixed scroll (30). In the compression mechanism(20), the thrust sliding surface (45) or the thrust sliding surface (35)includes the oil groove (80) formed thereon. The oil groove (80)communicates with the oil reservoir (18) in the casing (15) through thegroove communication passage (85). Accordingly, the pressure of thelubricating oil in the oil groove (80) becomes substantially equal tothe pressure of the lubricating oil stored in the casing (15). Thelubricating oil having flowed from the oil reservoir (18) into the oilgroove (80) through the groove communication passage (85) is supplied tothe thrust sliding surface (45) and the thrust sliding surface (35).

In the compression mechanism (20) of the first aspect, the orbitingscroll (40) may be sometimes tilted. In such a case, a clearance betweenthe thrust sliding surface (45) and the thrust sliding surface (35)increases, and consequently, the pressure of the oil groove (80) mayabruptly drop. On the other hand, in the first aspect of the presentdisclosure, since the bearing oil supply passage (70) is not incommunication with the oil groove (80), the abrupt pressure drop of theoil groove (80) does not cause the pressure of the bearing oil supplypassage (70) to change.

A second aspect of the present disclosure relates to the scrollcompressor of the first aspect, wherein the bearing oil supply passage(70) is provided with an oil supply pump (75) which is driven by thedriving shaft (60) and configured to suck the lubricating oil from theoil reservoir (18) in the casing (15) and to discharge the lubricatingoil, and the groove communication passage (85) is configured such thatthe lubricating oil is caused to flow through the groove communicationpassage (85) only by a pressure difference between the oil reservoir(18) in the casing (15) and the oil groove (80).

According to the second aspect, when the orbiting scroll (40) is tiltedand the pressure of the oil groove (80) decreases during operation ofthe compression mechanism (20), the lubricating oil in the oil reservoir(18) is caused to flow through the groove communication passage (85)toward the oil groove (80) by the pressure difference between the oilreservoir (18) in the casing (15) and the oil groove (80). On the otherhand, the bearing oil supply passage (70) is provided with the oilsupply pump (75). The oil supply pump (75) is driven by the drivingshaft (60), sucks the lubricating oil from the oil reservoir (18) in thecasing (15), and discharges the lubricating oil. The lubricating oildischarged by the oil supply pump (75) is supplied to the bearing in thecompression mechanism (20).

A third aspect of the present disclosure relates to the scrollcompressor of the second aspect, wherein the groove communicationpassage (85) is provided with at least one throttle for controlling aflow rate of the lubricating oil.

When the orbiting scroll (40) is tilted during operation of thecompression mechanism (20), the clearance between the thrust slidingsurface (45) and the thrust sliding surface (35) increases.Consequently, the lubricating oil easily flows out from the oil groove(80), and the flow rate of the lubricating oil in the groovecommunication passage (85) may become excessively high.

To address this problem, the groove communication passage (85) of thethird aspect is provided with the throttle. Accordingly, even in a statewhere the clearance between the thrust sliding surface (45) and thethrust sliding surface (35) has increased, the throttle controls theflow rate of the lubricating oil in the groove communication passage(85).

A fourth aspect of the present disclosure relates to the scrollcompressor of the third aspect, wherein the throttle is at least one rodmember (89) which is disposed in the groove communication passage (85)and includes, on its outer circumference, a spiral groove (89 e) throughwhich the lubricating oil is allowed to flow.

According to the fourth aspect, the rod member (89) having the spiralgroove (89 e) is disposed in the groove communication passage (85),thereby forming a narrow spiral channel on the outer circumference ofthe rod member (89) disposed in the groove communication passage (85).The narrow spiral channel on the outer circumference of the rod member(89) controls the flow rate of the lubricating oil having flowed o thegroove communication passage (85).

A fifth aspect of the present disclosure relate to the scroll compressorof the fourth aspect, wherein the at least one rod member (89) includesa plurality of rod members (89), and the plurality of rod members (89)are disposed in a plurality of locations of the groove communicationpassage (85).

According to the fifth aspect, the rod members (89) serving as thethrottles are disposed in the plurality of locations in the groovecommunication passage (85). If the groove communication passage (85) wasprovided with only one rod member (89), the rod member (89) provided inthe passage (85) would need to be a long one because the narrow channelwould need to be long to some extent in order to control the flow rateof the lubricating oil sufficiently. On the other hand, providing theplurality of rod members (89) in the plurality of locations in thegroove communication passage (85) as described above results in that thenarrow channels have a large length in total although each of the rodmembers (89) is short.

A sixth aspect of the present disclosure elate to the scroll compressorof the fifth aspect, further including a bearing (55) which is providedseparately from the compression mechanism (20) and supports the drivingshaft (60) in a rotatable manner, wherein the bearing (55) and the fixedscroll (30) respectively include therein a communicating path (83) andanother communicating path (81) which form part of the groovecommunication passage (85), and each of the communicating paths (83, 81)is provided with an associated one of the rod members (89).

According to the sixth aspect, the bearing (55) and the fixed scroll(30) respectively include therein the communicating path (83) and thecommunicating path (81) which form part of the groove communicationpassage (85), and each of the communicating paths(83, 81) is providedwith the associated one of the rod members (89) serving as thethrottles. If any one of the bearing (55) and the fixed scroll (30) wasprovided with one of the rod members (89), the narrow channel would needto be long to some extent to control the flow rate of the lubricatingnil sufficiently, and the rod member (89) and the communicating pathwhere the rod member (89) is disposed would need to be long. However,since both of the bearing (55) and the fixed scroll (30) include thereinthe communicating paths (83, 81) which are each provided with the rodmember (89), the narrow channels have a large length in total althougheach of the rod members (89) and the communicating paths (83, 81) isshort.

A seventh aspect of the present disclosure relates to the scrollcompressor of any of the first through the sixth aspects, furtherincluding: a motor (50) configured to drive and rotate the driving shaft(60); and a connection pipe (84) which is provided between the casing(15) and the motor (50) and forms part of the groove communicationpassage (85), wherein the connection pipe (84) is a resin pipe made of aresin material or a metal pipe having the outer circumferential surfacecoated with a resin material.

According to the seventh aspect, the connection pipe (84) which formspart of the groove communication passage (85) is provided between thecasing (15) and the motor (50).

If a metal pipe was provided on a side of the motor (50), it would benecessary to space the metal pipe from the motor (50) at a distancewhich ensures insulation, and accordingly, the diameter of the casing(15) would need to be increased in accordance with the distance betweenthe metal pipe and the motor (50).

In contrast, according to the seventh aspect, the connection pipe (84)is a resin pipe made of a resin material or a metal pipe having theouter circumferential surface coated with a resin material. Therefore,it is possible to ensure insulation without distancing the connectionpipe (84) from the motor (50).

An eighth aspect of the present disclosure relates to the scrollcompressor of any of the first through the seventh aspects, wherein alubricating oil inlet (88) of the groove communication passage (85) islocated higher than a suction inlet (76) of the bearing oil supplypassage (70).

Part of the lubricating oil supplied from the oil reservoir (18) in thecasing (15) to the thrust sliding surface (45) and the thrust slidingsurface (35) through the oil groove (80) flows into compressionchambers, and then, is discharged together with compressed refrigerantto the outside of the casing (15). Accordingly, the amount of thelubricating oil in the oil reservoir (18) in the casing (15) decreasesand the oil level is becoming low. When the oil level of the oilreservoir (18) in the casing (15) has become lower than the lubricatingoil inlet (76) of the bearing oil supply passage (70) and thelubricating oil inlet (88) of the groove communication passage (85), itis no longer possible to supply the lubricating oil from the oilreservoir (18) to the bearing of the driving shaft (60) and the oilgroove (80).

An insufficient amount of lubricating oil supplied to the bearing of thedriving shaft (60) may cause seizure and failure of the bearing. On theother hand, an insufficient amount of lubricating oil supplied to theoil groove (80) may cause an increase in friction force generatedbetween the thrust sliding surface (45) of the orbiting scroll (40) andthe thrust sliding surface (35) of the fixed scroll (30), andaccordingly, an increase in power consumption of the motor.

When an insufficient amount of the refrigeration oil is supplied to thebearing of the driving shaft (60), even for a short time, the bearingmay be fatally damaged and the compressor may become unable to operateproperly. On the other hand, when an insufficient amount of therefrigeration oil is supplied to the oil groove (80) only for a shorttime, the compressor does not suffer fatal damage although theperformance is temporary reduced by insufficient sealing of the thrustsliding surfaces (35, 45). That is, an oil shortage of the bearing ofthe driving shaft (60) must be dealt with more quickly than an oilshortage of the oil groove (80).

To address this problem, the eighth aspect has the configuration inwhich the lubricating oil inlet (88) of the groove communication passage(85) is located higher than the lubricating oil inlet (76) of thebearing oil supply passage (70). With this configuration, when thelubricating oil in the oil reservoir (18) in the casing (15) decreases,the oil level of the oil reservoir (18) first becomes lower than theinlet (88) of the groove communication passage (85), and supply of thelubricating oil to the oil groove (80) is stopped. Consequently, heamount of the lubricating oil discharged together with the refrigerantto the outside of the casing (15) decreases, and lowering of the oillevel of the oil reservoir (18) in the casing (15) is alleviated.

Advantages of the Invention

According to the first aspect of the present disclosure, any one of thethrust sliding surface (45) of the orbiting scroll (40) or the thrustsliding surface (35) of the fixed scroll (30) includes the oil groove(80) formed thereon. The bearing oil supply passage (70) which suppliesthe lubricating oil to the bearing in the compression mechanism (20) isnot in communication with the oil groove (80). Accordingly, even whenthe orbiting scroll (40) is tilted and the pressure of the oil groove(80) abruptly drops during operation of the compression mechanism (20),the pressure of the bearing oil supply passage (70) remains unchanged.

If the oil groove (80) and the bearing oil supply passage (70)communicated with each other, an abrupt pressure drop of the oil groove(80) would cause a decrease in the pressure of the bearing oil supplypassage (70). The pressure decrease of the bearing oil supply passage(70) would cause the lubricating oil to flow backward from the bearingin the compression mechanism (20) to the bearing oil supply passage(70), and would lead to a shortage of the lubricating oil for thebearing.

In contrast, the bearing oil supply passage (70) of the first aspect isnot in communication with the oil groove (80). An abrupt pressure dropof the oil groove (80) does not cause the pressure of the bearing oilsupply passage (70) to change. Therefore, according to the first aspect,even when the orbiting scroll (40) has been tilted and the pressure ofthe oil groove (80) has abruptly dropped, the lubricating oil is notallowed to flow backward from the bearing in the compression mechanism(20) to the bearing oil supply passage (70), and it is accordinglyensured that the lubricating oil continues to be supplied to the bearingin the compression mechanism (20) through the bearing oil supply passage(70). Consequently, lubrication of the bearing in the compressionmechanism (20) is ensured, and troubles such as seizure are prevented,thereby enabling improvement of the reliability of the scroll compressor(10).

According to the second aspect of the present disclosure, thelubricating oil discharged from the oil supply pump (75) driven by thedriving shaft (60) passes through the bearing oil supply passage (70),which is not in communication with the oil groove (80), to be suppliedto the bearing in the compression mechanism (20). Accordingly, even in astate where the orbiting scroll (40) has been tilted and the pressure ofthe oil groove (80) has abruptly dropped during operation of thecompression mechanism (20), the lubricating oil can be supplied to thebearing in the compression mechanism (20) in a stable manner. Therefore,according to the second aspect, it can be ensured that the lubricatingoil is supplied to the bearing in the compression mechanism (20)regardless of the pressure of the oil groove (80), thereby enablingimprovement of the reliability of the scroll compressor (10).

According to the third aspect of the present disclosure, the groovecommunication passage (85) is provided with the at least one throttle.Accordingly, even in a state where the orbiting scroll (40) has beentilted and the clearance between the thrust sliding surface (45) and thethrust sliding surface (35) has increased, the throttle controls theflow rate of the lubricating oil in the groove communication passage(85).

Here, tilting of the orbiting scroll (40) during operation of thecompression mechanism (20) may reduce a pressure loss caused when thelubricating oil passes through the clearance between the thrust slidingsurface (45) and the thrust sliding surface (35), and accordingly, thepressure acting on the thrust sliding surfaces (35, 45) increases tobecome approximate to the pressure of the lubricating oil in the oilgroove (80). In such a case, a force separating the orbiting scroll (40)from the fixed scroll (30) becomes strong, and the air tightness of thecompression chambers (21) may be reduced.

To address this problem, the groove communication passage (85) of thethird aspect is provided with the throttle. Accordingly, even in a statewhere the orbiting scroll (40) has been tilted, the flow rate of thelubricating oil flowing from the groove communication passage (85) intothe oil groove (80) and the pressure of the oil groove (80) are keptlow. Consequently, even when the orbiting scroll (40) has been tiltedduring operation of the compression mechanism (20), the pressure actingon the thrust sliding surfaces (35, 45) is kept low, and the forceseparating the orbiting scroll (40) from the fixed scroll (30) is notallowed to become excessively strong. On the other hand, the pressingforce acts on the orbiting scroll (40) to press the orbiting scroll (40)against the fixed scroll (30). Therefore, the orbiting scroll (40) whichhas been tilted during operation of the compression mechanism (20)quickly restores the original position by receiving the pressing force.According to the third aspect, it is possible to cause the orbitingscroll (40) which has been tilted during operation of the compressionmechanism (20) to quickly restore the original position, andaccordingly, decrease in performance of the scroll compressor (10) canbe alleviated by ensuring air tightness of the compression chambers(21).

According to the fourth aspect of the present disclosure, the throttlewhich controls the flow rate of the lubricating oil in the groovecommunication passage (85) can be easily provided simply by insertinginto the groove communication passage (85) the rod member (89) havingthe spiral groove (89 e) formed on the outer circumference. Furthermore,the cross-sectional area of the groove communication passage (85) can beeasily varied simply by changing the cross-sectional shape of the spiralgroove (89 e) formed on the outer circumference of the rod member (89).That is, use of the rod member (89) as the throttle increases the degreeof freedom of design and makes it easy to change the design.

When using the rod member (89) having the spiral groove (89 e) on theouter circumference as the throttle for controlling the flow rate of thelubricating oil in the groove communication passage (85), the narrowchannel formed with the spiral groove (89 e) needs to be long to someextent in order to obtain a sufficient throttle effect. Increasing thelength of the narrow channel by using a longer rod member (89), however,requires a longer space in which the longer rod member (89) is placed.In addition, installation of the longer rod member (89) may require muchtime and effort.

To address this problem, the fifth embodiment of the present disclosureis configured such that, a plurality of rod members (89) serving as thethrottles are provided in a plurality of locations of the groovecommunication passage (85). Accordingly, it is possible to increase thetotal length of the narrow channels by using the rod members (89) eachof which is short, and the flow rate of the lubricating oil in thegroove communication passage (85) can be sufficiently controlled. Inother words, providing the plurality of rod members (89) in theplurality of locations of the groove communication passage (85) makes itpossible to reduce the length of each of the rod members (89).Consequently, it is unnecessary to ensure long spaces for installationof the rod members (89), and the rod members (89) can be easilyinstalled.

According to the sixth aspect of the present disclosure, both of thebearing (55) and the fixed scroll (30) include the communicating paths(83, 81) which form part of the groove communication passage (85) andare provided with the rod members (89) serving as the throttles.Accordingly, even if each of rod members (89) and each of thecommunicating paths (81, 83) is short, the narrow channels can have alarge length in total. Consequently, the flow rate of the refrigerationoil in the groove communication passage (85) can be sufficientlycontrolled. In other words, designing each of the bearing member (55)and the fixed scroll (30) to include the associated communicating path(83, 81) and the associated rod member (89) provided in the associatedcommunicating path enables reduction of the length of each of the rodmembers (89). Consequently, it is unnecessary to ensure long spaces forinstallation of the rod members (89), and the rod members (89) can beeasily installed.

According to the seventh aspect of the present disclosure, a resin pipemade of a resin material or a metal pipe having the outercircumferential surface coated with a resin material is used as theconnection pipe (84) which is provided between the casing (15) and themotor (50) and forms part of the groove communication passage (85).Accordingly, it is possible to ensure insulation without distancing theconnection pipe (84) from the motor (50). It is consequently possible todesign the casing (15) to have a smaller diameter, and to downsize thescroll compressor.

The eighth aspect of the present disclosure has the configuration inwhich the lubricating oil inlet (88) of the groove communication passage(85) is located higher than the lubricating oil inlet (76) of thebearing oil supply passage (70). With this configuration, when thelubricating oil in the oil reservoir (18) in the casing (15) decreases,supply of the lubricating oil to the oil groove (80) is first stopped,and accordingly, the amount of the lubricating oil discharged togetherwith the refrigerant to the outside of the casing (15) is reduced.Consequently, lowering of the oil level of the oil reservoir (18) in thecasing (15) is alleviated. Therefore, according to the eighth aspect,even if the oil level of the oil reservoir (18) in the casing (15)begins to lower, lowering of the oil level of the oil reservoir (18) inthe casing (15) is alleviated by stopping oil supply to the oil groove(80). As a result, the oil level of the oil reservoir (18) does notbecome lower than the lubricating oil inlet (76) of the bearing oilsupply passage (70), and oil supply to the bearing of the driving shaft(60) can be ensured. That is, the oil supply to the bearing of thedriving shaft (60) is given a higher priority than the oil supply to theoil groove (80), and accordingly, fatal failures of the bearing of thedriving shaft (60) caused by seizure can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view illustrating an overallconfiguration of a scroll compressor according to Embodiment 1.

FIG. 2 is a longitudinal cross-sectional view illustrating aconfiguration of a main portion of the scroll compressor of Embodiment1.

FIG. 3 is a transverse cross-sectional view illustrating a configurationof a compression mechanism of the scroll compressor of Embodiment 1.

FIG. 4 is s longitudinal cross-sectional view illustrating aconfiguration of a main portion of a scroll compressor of Embodiment 2.

FIG. 5 is a longitudinal cross-sectional view illustrating an overallconfiguration of a scroll compressor according to Embodiment 3.

FIG. 6 is a longitudinal cross-sectional view illustratingconfigurations of first and second connection passages of the scrollcompressor of Embodiment 3.

FIG. 7 is a longitudinal cross-sectional view illustrating aconfiguration of a third connection passage of the scroll compressor ofEmbodiment 3.

FIG. 8 is a longitudinal cross-sectional view illustrating aconfiguration of a connection pipe of the scroll compressor ofEmbodiment 3.

FIG. 9 is a longitudinal cross-sectional view illustrating a mainportion of a conventional scroll compressor.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described in detail withreference to the drawings.

Embodiment

Embodiment 1 of the present disclosure is now described. A scrollcompressor (10) of this embodiment is a hermetic compressor. The scrollcompressor (10) is connected to a refrigerant circuit which performs arefrigerating cycle, and configured to suck and compress the refrigerantof the refrigerant circuit.

<Overall Configuration of Scroll Compressor>

As illustrated in FIG. 1, the scroll compressor (10) includes a casing(15), and a compression mechanism (20), a motor (50), a lower bearingmember (55), and a driving shaft (60) are housed in the inner space ofthe casing (15). The casing (15) is a hermetic container having avertically oriented cylindrical shape. In the inner space of the casing(15), the compression mechanism (20), the motor (50), and the lowerbearing member (55) are arranged in this order from top to bottom. Thedriving shaft (60) is disposed such that the axial direction of thedriving shaft (60) is along the vertical direction of the casing (15).The structure of the compression mechanism (20) will be detailed later.

The casing (15) is provided with a suction pipe (16) and a dischargepipe (17). Both of the suction pipe (16) and the discharge pipe (17)penetrate the wall of the casing (15). The suction pipe (16) isconnected to the compression mechanism (20). The discharge pipe (17)opens in room between the motor (50) and the compression mechanism (20)in the inner space of the casing (15).

The lower bearing member (55) includes a central cylindrical portion(56), and is provided with three arms (57), only one of which isillustrated in FIG. 1. The central cylindrical portion (56) has a nearlycylindrical shape. Each of the arms (57) extends outwardly from theouter circumferential surface of the central cylindrical portion (56).The angles formed between adjacent ones of the three arms (57) providedon the lower bearing member (55) are substantially equal to one another.The end of each of the arms (57) is secured to the casing (15). Abearing metal (58) penetrates a part of the central cylindrical portion(56) near its upper end. The bearing metal (58) is penetrated by anauxiliary journal portion (67) of the driving shaft (60) which will bedescribed later. The central cylindrical portion (56) forms a journalbearing which supports the auxiliary journal portion (67).

The motor (50) includes a stator (51) and a rotor (52). The stator (51)is secured to the casing (15). The rotor (52) is disposed coaxially withthe stator (51). The rotor (52) is penetrated by a main shaft portion(61) of the driving shaft (60) which will be described later.

The driving shaft (60) includes the main shaft portion (61), a balanceweight (62), and an eccentric portion (63). The balance weight (62) islocated in an intermediate part in the axial direction of the main shaftportion (61). Part of the main shaft portion (61) located below thebalance weight (62) penetrates the rotor (52) of the motor (50). Part ofthe main shaft portion (61) located above the balance weight (62) formsa main journal portion (64). The auxiliary journal portion (67) islocated below the part of the in shaft portion (61) penetrating therotor (52). The main journal portion (64) penetrates a bearing metal(28) provided in a central bulge portion (27) of a housing (25). Theauxiliary journal portion (67) penetrates the bearing metal (58)provided in the central cylindrical portion (56) of the lower bearingmember (55).

The eccentric portion (63) has a circular column shape having a diametersmaller than the diameter of the main journal portion (64), and projectsfrom the upper end surface of the main journal portion (64). The shaftcenter of the eccentric portion (63) is parallel with and eccentricrelative to the shaft center of the main journal portion (64) (i.e., theshaft center of the main shaft portion (61)). The eccentric portion (63)penetrates a bearing metal (44) provided in a cylindrical portion (43)of an orbiting scroll (40).

The driving shaft (60) has an oil supply passage (77) formed therein.The oil supply passage (77) includes a main passage (74) and threebranch passages (71-73). The main passage (74) extends along the shaftcenter of the driving shaft (60), and has an end which opens at thelower end of the main shaft portion (61) and the other end which openson the upper end surface of the eccentric portion (63). The first branchpassage (71) is located in the eccentric portion (63). The first branchpassage (71) outwardly extends from the main passage (74) in a radialdirection of the eccentric portion (63) and opens on the outercircumferential surface of the eccentric portion (63). The second branchpassage (72) is located in the main journal portion (64). The secondbranch passage (72) outwardly extends from the main passage (74) in aradial direction of the main journal portion (64) and opens on the outercircumferential surface of the main journal portion (64). The thirdbranch passage (73) is located in the auxiliary journal portion (67).The third branch passage (73) outwardly extends from the main passage(74) in a radial direction of the auxiliary journal portion (67) andopens on the outer circumferential surface of the auxiliary journalportion (67).

An oil supply pump (75) is mounted at the lower end of the driving shaft(60). The oils supply pump (75) is a trochoid pump which is driven bythe driving shaft (60). The oil supply pump (75) is disposed near thestarting end of the main passage (74) of the oil supply passage (77).The oil supply pump (75) has, at the lower end, a suction inlet (76)which opens downwardly and through which a refrigeration oil serving aslubricating oil is sucked. Note that the oil supply pump (75) is notlimited to the trochoid pump and may be any displacement e pump drivenby the driving shaft (60). Accordingly, the oil supply pump (75) may bea gear pump, for example. The oil supply pump (75) and the oil supplypassage (77) together form a bearing oil supply passage (70) whichsupplies the refrigeration oil to journal bearings of the compressionmechanism (20) which will be described later. The suction inlet (76) ofthe oil supply pump (75) serves as a refrigeration oil inlet for thebearing oil supply passage (70).

The refrigeration oil serving as lubricating oil is stored in a bottomportion of the casing (15). That is, the casing (15) has an oilreservoir (18) in its bottom portion. When the driving shaft (60)rotates, the oil supply pump (75) sucks the refrigeration oil from theoil reservoir (18) and discharges the same. The refrigeration oildischarged from the oil supply pump (75) flows through the main passage(74). The refrigeration oil flowing through the main passage (74) issupplied to the lower bearing member (55) and sliding parts of thecompression mechanism (20) and the driving shaft (60). Since the oilsupply pump (75) is a displacement pump, the rate of the refrigerationoil in the main passage (74) is proportional to the rotation speed ofthe driving shaft (60).

<Configuration of Compression Mechanism>

As illustrated in FIG. 2, the compression mechanism (20) includes thehousing (25), a fixed scroll (30), and the orbiting scroll (40). Thecompression mechanism (20) is provided with an Oldham's coupling (24)for controlling rotation of the orbiting scroll (40).

The housing (25) has a disk shape with a large wall thickness, and theouter circumferential edge of the housing (25) is secured to the casing(15). The housing (25) has a central recess (26) and an annularprojection (29) formed in its central part. The central recess (26) is arecess which has a circular column shape and opens on the upper surfaceof the housing (25). The annular projection (29) surrounds the centralrecess (26) and projects from the upper surface of the housing (25). Theannular projection (29) has a flat top surface on which a ring-shapedgroove is formed along the circumference of the annular projection (29).A seal ring (29 a) is fitted in this groove.

The housing (25) has the central bulge portion (27) formed thereon. Thecentral bulge portion (27) is located below the central recess (26) andbulges downward. The central bulge portion (27) has a through hole whichvertically penetrates the central bulge portion (27). The bearing metal(28) penetrates through this through hole. The main journal portion (64)of the driving shaft (60) penetrates the bearing metal (28) of thecentral bulge portion (27). The central bulge portion (27) forms thejournal bearing which supports the main journal portion (64).

The fixed scroll (30) and the orbiting scroll (40) are disposed on thehousing (25). The fixed scroll (30) is secured to the housing (25) with,e.g. bolts. On the other hand, the orbiting scroll (40) is engaged withthe housing (25) via the Oldham's coupling (24), and is provided movablyrelative to the housing (25). The orbiting scroll (40), which is engagedwith driving shaft (60), performs orbital motion,

The orbiting scroll (40) is a component into which an end plate (41), alap (42), and the cylindrical portion (43) are integrated. The end plate(41) of the orbiting scroll (40) has a disk-like shape. The lap (42) ofthe orbiting scroll (40) is formed in a spiral-shaped wall, and projectsfrom the front side of the end plate (41) (i.e. from the upper surfaceof the end plate (41) in FIGS. 1 and 2). The cylindrical portion (43)has a cylindrical shape and projects from the backside of the end plate(41) (i.e. from the lower surface of the end plate (41) in FIGS. 1 and2).

The backside of the end plate (41) of the orbiting scroll (40) is insliding contact with the seal ring (29 a) disposed on the annularprojection (29) of the housing (25). On the other hand, the cylindricalportion (43) of the orbiting scroll (40) downwardly penetrates thecentral recess (26) of the housing (25). The bearing metal (44)penetrates the cylindrical portion (43). The eccentric portion (63) ofthe driving shaft (60) which will be detailed later upwardly penetratesthe bearing metal (44) of the cylindrical portion (43). The cylindricalportion (43) forms the journal bearing which slides on the eccentricportion (63).

The fixed scroll (30) is a component into which an end plate (31), a lap(32), and an outer circumferential portion (33) are integrated. The endplate (31) of the fixed scroll (30) has a disk-like shape. The lap (32)of the fixed scroll (30) is formed in a spiral-shaped wall, and projectsfrom the front side of the end plate (31) (i.e. from the lower surfaceof the end plate (31) in FIGS. 1 and 2). The outer circumferentialportion (33) has a ring shape with a large wall thickness, anddownwardly extends from the outer circumference of the end plate (31) tosurround the lap (32).

The end plate (31) has a discharge port (22) formed therein. Thedischarge port (22) is a through hole formed near the center of the endplate (31), and penetrates the end plate (31) in the thicknessdirection. The suction pipe (16) penetrates a part of the end plate (31)near the outer circumference.

The compression mechanism (20) has a discharged gas passage (23) formedtherein. The discharged gas passage (23) has the starting end whichcommunicates with the discharge port (22). Although not shown, thedischarged gas passage (23) extends from the fixed scroll (30) to thehousing (25), and has the other end which opens on the lower surface ofthe housing (25).

In the compression mechanism (20), the fixed scroll (30) and theorbiting scroll (40) are disposed such that the front side of the endplate (31) faces the front side of the end plate (41), and the lap (32)and the lap (42) are engaged with each other. Accordingly, in thecompression mechanism (20), a plurality of compression chambers (21) areformed by engagement of the laps (32, 42).

In the compression mechanism (20), the end plate (41) of the orbitingscroll (40) is in sliding contact with the outer circumferential portion(33) of the fixed scroll (30). Specifically, on the front side of theend plate (41) (i.e. on the upper surface of the end plate (41) in FIGS.1 and 2), a part located outward relative to the lap (42) serves as athrust sliding surface (45) which is in sliding contact with the fixedscroll (30). On the other hand, on the outer circumferential portion(33) of the fixed scroll (30), the top surface (i.e., the lower surfaceof the outer circumferential portion (33) in FIGS. 1 and 2) is insliding contact with the thrust sliding surface (45) of the orbitingscroll (40). In the outer circumferential portion (33), a part which isin sliding contact with the thrust sliding surface (45) serves as athrust sliding surface (35) of the fixed scroll (30).

As illustrated in FIGS. 2 and 3, the outer circumferential portion (33)of the fixed scroll (30) has an oil groove (80) and a connection passage(86) formed therein. The oil groove (80) is a groove formed bydepressing the thrust sliding surface (35) of the outer circumferentialportion (33), and has a ring shape surrounding the lap (32). Theconnection passage (86) has an end which communicates with the oilgroove (80). The connection passage (86) extends from the end toward theouter circumference of the outer circumferential portion (33). Acapillary tube (87) which will be detailed later is connected to a partnear the other end of the connection passage (86). The connectionpassage (86) and the capillary tube (87) together form a groovecommunication passage (85).

The capillary tube (87) is a thin copper tube with an inside diameter of0.5-1.0 mm, and serves as a throttle. The capillary tube (87) extendsalong the inner surface of the casing (15). Specifically, the capillarytube (87), which passes through a through hole formed in the housing(25) and penetrates the outer circumferential portion (33) of the fixedscroll (30), has the upper end communicating with the connection passage(86). The capillary tube (87) also penetrates through a core-cut partformed in the stator (51) of the motor (50) to reach the oil reservoir(18). Thus, the capillary tube (87) has the lower end soaked in therefrigeration oil stored in the bottom portion of the casing (15).

The lower end opening (88) of the capillary tube (87) serves as arefrigeration oil inlet through which the refrigeration oil is caused toflow into the groove communication passage (85). The lower end opening(88) of the capillary tube (87) is located higher than the suction inlet(76) of the oil supply pump (75). In this embodiment, the lower endopening (88) of the capillary tube (87) is located about 10 mm above thesuction inlet (76) of the oil supply pump (75). That is, the inlet ofthe groove communication passage (85) is located higher than therefrigeration oil inlet of the bearing oil supply passage (70).

In this embodiment, the groove communication passage (85) constituted bythe connection passage (86) and the capillary tube (87) connects the oilgroove (80) only to the oil reservoir (18) in the casing (15).Accordingly, in this embodiment, the oil supply passage (77) formed inthe driving shaft (60) is not in communication with the oil groove (80)located on the fixed scroll (30). That is, the bearing oil supplypassage (70) is not in communication with the oil groove (80).

Operation

Operation by the scroll compressor (10) is now described.

<Operation to Compress Refrigerant>

In the scroll compressor (10), when the motor (50) is supplied withelectricity, the driving shaft (60) drives the orbiting scroll (40).Since rotation of the orbiting scroll (40) is controlled by the Oldham'scoupling (24), the orbiting scroll (40) only performs orbital motionwithout rotating.

When the orbiting scroll (40) performs orbital motion, the gaseousrefrigerant with a low pressure having flowed into the compressionmechanism (20) through the suction pipe (16) is sucked into thecompression chamber (21) from the portions near the outercircumferential ends of the lap (32) and the lap (42). When the orbitingscroll (40) further moves, the compression chamber (21) becomes isolatedfrom the suction pipe (16) to enter a completely closed state. Thecompression chamber (21) then moves along the lap (32) and the lap (42)toward the inner circumferential ends of the laps (32, 42). During thismovement, the volume of the compression chamber (21) graduallydecreases, and accordingly, the gaseous refrigerant in the compressionchamber (21) is compressed in a gradual manner.

After the gradual decrease in the volume of the compression chamber (21)caused by the movement of the orbiting scroll (40), the compressionchamber (21) comes into communication with the discharge port (22). Thecompressed refrigerant (i.e., the gaseous refrigerant with a highpressure) in the compression chamber (21) flows through the dischargeport (22) to enter the discharge gas passage (23), and then isdischarged to the inner space of the casing (15). In the inner space ofthe casing (15), the high-pressure gaseous refrigerant having beendischarged from the compression mechanism (20) is initially guided toroom below the stator (51) of the motor (50), and then, allowed to flowupwardly through, e.g., a gap between the rotor (52) and the stator(51). Thereafter, the gaseous refrigerant passes through the dischargepipe (17) to flow out to the outside of the casing (15).

In room below the housing (25) located in the inner space of the casing(15), the high-pressure gaseous refrigerant having been discharged fromthe compression mechanism (20) is flowing, and the room below thehousing (25) has a pressure substantially equal to the pressure of thehigh-pressure gaseous refrigerant. Accordingly, the refrigeration oilstored in the oil reservoir (18) in the casing (15) has a pressuresubstantially equal to the pressure of the high-pressure gaseousrefrigerant.

On the other hand, room above the housing (25) located in the innerspace of the casing (15), although not shown, communicates with thesuction pipe (16), and has a pressure approximate to the pressure of thelow-pressure gaseous refrigerant sucked into the compression mechanism(20). Accordingly, in the compression mechanism (20), room near theouter circumference of the end plate (41) of the orbiting scroll (40)has a pressure approximate the pressure of the low-pressure gaseousrefrigerant.

<Operation to Supply Oil to Compression Mechanism>

During operation of the scroll compressor (10), the driving shaft (60)rotates and drives the oil supply pump (75), and the refrigeration oilstored in the bottom portion of the casing (15) is sucked and suppliedto the main passage (74) of the oil supply passage (77). Part of therefrigeration oil flowing through the main passage (74) flows into thebranch passages (71-73) and the remainder of the refrigeration oil flowsout from the upper end of the main passage (74).

The refrigeration oil having flowed into the first branch passage (71)is supplied to a gap between the eccentric portion (63) and the bearingmetal (44) to be used to lubricate and cool the eccentric portion (63)and the bearing metal (44). The refrigeration oil having flowed into thesecond branch passage (72) is supplied to a gap between the main journalportion (64) and the bearing metal (28) to be used to lubricate and coolthe main journal portion (64) and the bearing metal (28). Therefrigeration oil having flowed into the third branch passage (73) issupplied to a gap between the auxiliary journal portion (67) and thebearing metal (58) to be used to lubricate and cool the auxiliaryjournal portion (67) and the bearing metal (58). In addition, in thecompression mechanism (20), the sliding parts of the orbiting scroll(40) and the Oldham's coupling (24) and the sliding parts of theorbiting scroll (40) and the fixed scroll (30) are supplied with therefrigeration oil.

<Operation to Press Orbiting Scroll>

The compression mechanism (20) of this embodiment is configured suchthat the orbiting scroll (40) is pressed against the fixed scroll (30)by using the refrigeration oil supplied from the oil reservoir (18)located in the casing (15).

Specifically, in the compression mechanism (20), the backside of the endplate (41) of the orbiting scroll (40) is in sliding contact with theseal ring (29 a). The refrigeration oil having flowed out from theterminal end of the main passage (74) of the oil supply passage (77) ispresent in the central recess (26) located inside that seal ring (29 a).This refrigeration oil has a pressure approximate to the pressure of therefrigeration oil in the oil reservoir (18).

In the orbiting scroll (40), the pressure of the refrigeration oilhaving flowed out from the main passage (74) acts on a part of thebackside of the end plate (41) located inside the seal ring (29 a), andon the surface of the cylindrical portion (43). Consequently, a pressingforce toward the fixed scroll (30) (i.e., an upward force in thisembodiment) acts on the orbiting scroll (40). As a result, also duringoperation of the compression mechanism (20), the orbiting scroll (40) iskept pressed against the fixed scroll (30), thereby ensuring airtightness of the compression chambers (21).

However, the pressing force acting on the orbiting scroll (40) sometimesbecomes too strong. The excessively strong pressing force increases thefriction force acting between the orbiting scroll (40) and the fixedscroll (30), and accordingly, causes an increase in power consumption ofthe motor (50).

To address this problem, the scroll compressor (10) of this embodimentincludes the oil groove (80) which communicates with the oil reservoir(18) in the casing (15) through the groove communication passage (85)and which is kept filled with the high-pressure refrigeration oil. Onthe other hand, the compression chamber (21) adjacent to the oil groove(80) (i.e., the compression chamber (21) formed near the outermost partsof the laps (32, 42)) has a pressure approximate to the pressure of thelow-pressure refrigerant sucked into the compression chamber (21) andwhich is lower than the pressure of the refrigeration oil in the oilgroove (80). Consequently, the refrigeration oil in the oil groove (80)gradually flows out to enter a clearance between the thrust slidingsurface (45) and the thrust sliding surface (35) to be used to lubricatethe thrust sliding surfaces (35, 45).

In this manner, the scroll compressor (10) of this embodiment ensuresthat the refrigeration oil is supplied to the clearance between thethrust sliding surface (45) and the thrust sliding surface (35).Accordingly, even in a state where the orbiting scroll (40) is stronglypressed against the fixed scroll (30), the friction force between thethrust sliding surface (45) and the thrust sliding surface (35) does notbecome excessively strong.

<Operation Performed When Orbiting Scroll is Tilted>

In the orbiting scroll (40) of the scroll compressor (10), the internalpressure of the compression chambers (21) acts on the lap (42)projecting from the front side of the end plate (41), and a load fromthe eccentric portion (63) acts on the cylindrical portion (43)projecting from the backside of the end plate (41). The line of actionof the gas pressure acting on the lap (42) and the line of action of theload acting on the cylindrical portion (43) intersect the axialdirection of the orbiting scroll (40) at right angles but do notintersect each other. Accordingly, during operation of the compressionmechanism (20), a moment acts on the orbiting scroll (40) in a directiontilting the orbiting scroll (40). If the pressing force acting on theorbiting scroll (40) is sufficiently strong, the orbiting scroll (40) isnot tilted even by the moment acting thereon.

However, in an operational state where the pressing force isinsufficiently strong, the orbiting scroll (40) is sometimes tilted,thereby increasing the clearance between the thrust sliding surface (45)and the thrust sliding surface (35). For example, the pressing force maybecome insufficiently strong in an operational state where the pressuredifference between the low-pressure gaseous refrigerant sucked into thecompression mechanism (20) and the high-pressure gaseous refrigerantdischarged from the compression mechanism (20) is small, or in anoperational state where the rotation speed of the driving shaft (60) isconsiderably low (e.g., 10-20 rotations per second).

As described above, in the compression mechanism (20), the pressure ofthe room near the outer circumference of the end plate (41) isapproximate to the pressure of the low-pressure gaseous refrigerantsucked into the compression mechanism (20). On the other hand, when theorbiting scroll (40) is tilted and the clearance between the thrustsliding surface (45) and the thrust sliding surface (35) increases, aflow resistance in the clearance between the thrust sliding surfaces(35, 45) decreases. Accordingly, tilting of the orbiting scroll (40) maycause a large amount of the refrigeration oil to spout out from the oilgroove (80) to the room near the outer circumference of the end plate(41).

In addition, tilting of the orbiting scroll (40) may reduce a pressureloss caused when the refrigeration oil passes through the clearancebetween the thrust sliding surface (45) and the thrust sliding surface(35), and accordingly, the pressure acting on the thrust slidingsurfaces (35, 45) increases to become approximate to the pressure of therefrigeration oil in the oil groove (80). In such a case, a forceseparating the orbiting scroll (40) from the fixed scroll (30) becomesstrong, and the air tightness of the compression chambers (21) may bereduced.

To address this problem, the scroll compressor (10) of this embodimentincludes the capillary tube (87) provided in the groove communicationpassage (85). Even in a state where the orbiting scroll (40) has beentilted and the clearance between the thrust sliding surface (45) and thethrust sliding surface (35) has increased, the capillary tube (87)controls the flow rate of the refrigeration oil in the groovecommunication passage (85).

In this manner, in the compression mechanism (20) of this embodiment,even in a state where the orbiting scroll (40) has been tilted, the flowrate of the refrigeration oil flowing from the groove communicationpassage (85) to the oil groove (80) and the pressure of the oil groove(80) are kept low. Consequently, even if the orbiting scroll (40) istilted during operation of the compression mechanism (20), the pressureacting on the thrust sliding surfaces (35, 45) is kept low, and theforce separating the orbiting scroll (40) from the fixed scroll (30) isnot allowed to become excessively strong. On the other hand, thepressing force acts on the orbiting scroll (40) to press the orbitingscroll (40) against the fixed scroll (30). Therefore, the orbitingscroll (40) which has been tilted during operation of the compressionmechanism (20) quickly restores the original position by receiving thepressing force.

Here, if the pressure loss caused when the refrigeration oil moves fromone end to the other end of the groove communication passage (85) is toosmall and tilting of the orbiting scroll (40) causes the pressure in theoil groove (80) to decrease, the flow rate of the refrigeration oil inthe groove communication passage (85) abruptly increases and a largeamount of the refrigeration oil spouts from the terminal end of thegroove communication passage (85). On the other hand, if the pressureloss caused when the refrigeration oil moves from an end to the otherend of the groove communication passage (85) is too large, it may take alonger time for the pressure of the oil groove (80) to becomesufficiently high after tilting of the orbiting scroll (40) has beeneliminated, and an insufficient amount of the refrigeration oil may besupplied to the clearance between the thrust sliding surface (45) andthe thrust sliding surface (35).

To address this problem, in this embodiment, the connection passage (86)and the capillary tube (87) together form the groove communicationpassage (85). According to this embodiment, the inside diameter and thelength of the capillary tube (87) are adjusted such that the pressureloss caused when the refrigeration oil moves from one end to the otherof the groove communication passage (85) becomes an appropriate value.

<Operation to Control Lowering of Oil Level of Oil Reservoir>

As described above, in the scroll compressor (10) of this embodiment,the refrigeration oil in the oil groove (80) gradually flows out toenter the clearance between the thrust sliding surface (45) of theorbiting scroll (40) and the thrust sliding surface (35) of the fixedscroll (30) to be used to lubricate the thrust sliding surfaces (35,45). Part of the refrigeration oil having been used to lubricate thethrust sliding surfaces flows into the compression chamber (21) adjacentto the oil groove (80), and is then discharged together with the gaseousrefrigerant to the inner spacer of the casing (15). The dischargedrefrigeration oil and the gaseous refrigerant are dispersed within theinner space of the casing (15), and then, are initially guided to roombelow the stator (51) of the motor (50). Part of the refrigeration oildrops to be stored in the oil reservoir (18) whereas the remainder ofthe refrigeration oil and the gaseous refrigerant flow upwardly through,e.g., a gap between the rotor (52) and the stator (51) to be dischargedto the outside of the casing (15) through the discharge pipe (17).

The refrigeration oil which has been discharged together with thegaseous refrigerant to the outside of the casing (15) in the abovedescribed manner circulates, together with the refrigerant, through therefrigerant circuit to which the scroll compressor (10) is connected,and then, is sucked again into the scroll compressor (10). Therefrigeration oil having been sucked into the scroll compressor (10) isdischarged together with the compressed gaseous refrigerant to the innerspace of the casing (15). Part of the refrigeration oil is returned tothe oil reservoir (18) in the casing (15).

Meanwhile, depending on operational states, return of the refrigerationoil to casing (15) of the scroll compressor (10) is sometimes impeded.For example, a low temperature of an evaporator causes an increase inthe viscosity of the refrigeration oil. This increase in the viscositycauses the refrigeration oil to easily accumulate in the evaporator, andresults in an impediment to return of the refrigeration oil to thescroll compressor (10). When this operation state continues, the amountof the refrigeration oil discharged together with gaseous refrigerantfrom the casing (15) becomes larger than the amount of refrigeration oilreturned to the casing (15). Accordingly, the amount of therefrigeration oil in the oil reservoir (18) decreases, resulting in thatthe oil level is lowered. When the oil level of the oil reservoir (18)in the casing (15) becomes lower than the suction inlet (76) of the oilsupply pump (75) (i.e., the refrigeration oil inlet of the bearing oilsupply passage (70)) and the lower end opening (88) of the capillarytube (87) (i.e., the refrigeration oil inlet of the groove communicationpassage (85)), it becomes impossible to supply the refrigeration oilfrom the oil reservoir (18) to the journal bearings and the oil groove(80) of the compression mechanism (20).

An insufficient amount of the refrigeration oil supplied to the journalbearings of the compression mechanism (20) may cause seizure and failureof the journal bearings. On the other hand, an insufficient amount ofthe refrigeration oil supplied to the oil groove (80) may cause anincrease in the friction force between the thrust sliding surface (45)of the orbiting scroll (40) and the thrust sliding surface (35) of thefixed scroll (30), and an increase in the power consumption of themotor.

When an insufficient amount of the refrigeration oil is supplied to thebearing of the driving shaft (60), even for a short time, the journalbearings may be fatally damaged and the compressor may become unable tooperate properly. On the other hand, when an insufficient amount of therefrigeration oil is supplied to the oil groove (80) only for a shorttime, the compressor does not suffer fatal damage although theperformance is temporary reduced by insufficient sealing of the thrustsliding surfaces (35, 45). That is, an oil shortage of the journalbearings of the compression mechanism (20) must be dealt with morequickly than an oil shortage of the oil groove (80).

To address this problem, the scroll compressor (10) of this embodimenthas the configuration in which the lower end opening (88) of thecapillary tube (87) serving as the refrigeration oil inlet of the groovecommunication passage (85) is located higher than the suction inlet (76)of the oil supply pump (75) serving as the refrigeration oil inlet ofthe bearing oil supply passage (70). With this configuration, when therefrigeration oil in the oil reservoir (18) in the casing (15)decreases, the oil level of the oil reservoir (18) first becomes lowerthan the lower end opening (88) of the capillary tube (87), and supplyof the refrigeration oil to the oil groove (80) is stopped. Thus, evenwhen the oil level of the oil reservoir (18) in the casing (15) islowered, the stop of supply of the refrigeration oil to the oil groove(80) causes a decrease in the amount of the refrigeration oil dischargedtogether with the refrigerant to the outside of the casing (15).Consequently, the amount of the refrigeration oil discharged to theoutside of the casing (15) falls short of the amount of therefrigeration oil returned to the inside of the casing (15), andlowering of the oil level of the oil reservoir (18) in the casing (15)is alleviated. In this manner, lowering of the oil level of the oilreservoir (18) in the casing (15) is alleviated such that the oil levelof the oil reservoir (18) will not become lower than the suction inlet(76) of the bearing oil supply passage (70) and oil supply to thejournal bearings of the compression mechanism (20) is ensured.

Advantages of Embodiment 1

According to this embodiment, the fixed scroll (30) has the oil groove(80) formed on the thrust sliding surface (35). The bearing oil supplypassage (70) supplying the refrigeration oil to the journal bearings ofthe compression mechanism (20) is not in communication with the oilgroove (80). Therefore, even when the orbiting scroll (40) is tilted andthe pressure of the oil groove (80) abruptly drops during operation ofthe compression mechanism (20), the pressure of the bearing oil supplypassage (70) remains unchanged.

If the oil groove (80) and the bearing oil supply passage (70)communicated with each other, an abrupt pressure drop of the oil groove(80) would cause a decrease in the pressure of the bearing oil supplypassage (70). The pressure decrease of the bearing oil supply passage(70) would cause the refrigeration oil to flow backward from the journalbearings of the compression mechanism (20) to the bearing oil supplypassage (70), and would lead to a shortage of the lubricating oil forthe journal bearings.

In contrast, the bearing oil supply passage (70) of this embodiment isnot in communication with the oil groove (80). An abrupt pressure dropof the oil groove (80) does not cause the pressure of the bearing oilsupply passage (70) to change. Therefore, according to this embodiment,even if the orbiting scroll (40) is tilted and the pressure of the oilgroove (80) abruptly drops, the refrigeration oil is not allowed to flowbackward from the journal bearings of the compression mechanism (20) tothe bearing oil supply passage (70), and it is accordingly ensured thatthe refrigeration oil continues to be supplied to the journal bearingsof the compression mechanism (20) through the bearing oil supply passage(70). Consequently, lubrication of the journal bearings of thecompression mechanism (20) is ensured, and troubles such as seizure areprevented, thereby enabling improvement of the reliability of the scrollcompressor (10).

In this embodiment, the refrigeration oil discharged from the oil supplypump (75) driven by the driving shaft (60) passes through the bearingoil supply passage (70), which is not in communication with the oilgroove (80), to be supplied to the journal bearings of the compressionmechanism (20). Accordingly, even in a state where the orbiting scroll(40) has been tilted and the pressure of the oil groove (80) hasabruptly dropped during operation of the compression mechanism (20), therefrigeration oil can be supplied to the journal bearings of thecompression mechanism (20) in a stable manner. Therefore, according tothis embodiment, supply of the refrigeration oil to the journal bearingsof the compression mechanism (20) is endured regardless of the pressureof the oil groove (80), and accordingly, it can be ensured that troublessuch as seizure of the journal bearings are avoided.

When the orbiting scroll (40) is tilted under conditions in which thepressure loss caused when the refrigeration oil moves from one end tothe other of the groove communication passage (85) is too small, theclearance between the thrust sliding surface (45) and the thrust slidingsurface (35) is increased by the tilting of the orbiting scroll (40),and consequently, a large amount of the refrigeration oil spouts fromthe terminal end of the groove communication passage (85). Underconditions in which the pressure loss caused when the refrigeration oilmoves from one end to the other of the groove communication passage (85)is too large, it may take a longer time for the pressure of the oilgroove (80) to become sufficiently high after tilting of the orbitingscroll (40) has been eliminated, and an insufficient amount of therefrigeration oil may be supplied to the clearance between the thrustsliding surface (45) and the thrust sliding surface (35).

To address this problem, in this embodiment, the capillary tube (87)forms part of the groove communication passage (85) such that thepressure loss caused when the refrigeration oil moves from one end tothe other of the groove communication passage (85) is adjusted to anappropriate value. Accordingly, even in a state where the orbitingscroll (40) has been tilted, it is possible to prevent the flow rate ofthe refrigeration oil in the groove communication passage (85) fromincreasing excessively. Consequently, even when the orbiting scroll (40)is tilted, the pressure of the oil groove (80) can be kept low bycontrolling the flow rate of the refrigeration oil flowing from thegroove communication passage (85) into the oil groove (80), andaccordingly, it is possible to cause the tilted orbiting scroll (40) torestore the original position quickly. In addition, once the orbitingscroll (40) has restored the original position, the pressure of the oilgroove (80) can be quickly increased to ensure that a sufficient amountof the refrigeration oil is supplied to the clearance between the thrustsliding surface (45) and the thrust sliding surface (35).

In the scroll compressor (10) of this embodiment, the lower end opening(88) of the capillary tube (87) serving as the refrigeration oil inletof the groove communication passage (85) is located higher than thesuction inlet (76) of the oil supply pump (75) serving as therefrigeration oil inlet of the bearing oil supply passage (70).Accordingly, lowering of the oil level of the oil reservoir (18) in thecasing (15) first stops supply of the refrigeration oil to the oilgroove (80), and the amount of the refrigeration oil discharged togetherwith the refrigerant to the outside of the casing (15) is reduced.Consequently, the amount of the refrigeration oil discharged to theoutside of the casing (15) falls short of the amount of therefrigeration oil returned to the inside of the casing (15), andlowering of the oil level of the oil reservoir (18) in the casing (15)is alleviated. Therefore, according to the scroll compressor (10) ofthis embodiment, even if the oil level of the oil reservoir (18) in thecasing (15) begins to lower, lowering of the oil level of the oilreservoir (18) in the casing (15) is alleviated by stopping supply ofthe refrigeration oil to the oil groove (80) such that the oil level ofthe oil reservoir (18) will not become lower than the inlet (76) of theoil supply pump (75), and the oil supply to the journal bearings of thecompression mechanism (20) can be ensured. That is, the oil supply tothe journal bearings of the compression mechanism (20) is given a higherpriority than the oil supply to the oil groove (80), and fatal failuresof the journal bearings can be prevented.

Embodiment 2

Embodiment 2 of the present disclosure will be described below, focusingon differences between a scroll compressor (10) of Embodiment 2 and thatof Embodiment 1.

As illustrated in FIG. 4, in a compression mechanism (20) of thisembodiment, an oil groove (80) is formed not on a fixed scroll (30) buton an orbiting scroll (40). Specifically, the oil groove (80) of thisembodiment is located on an end plate (41) of the orbiting scroll (40).The oil groove (80) is a groove formed by depressing a thrust slidingsurface (45) of the end plate (41), and has a ring shape surrounding alap (42) of the orbiting scroll (40). In this embodiment, a terminal endof a connection passage (86) opens on a thrust sliding surface (35) ofthe fixed scroll (30). The terminal end of the connection passage (86)has a large width such that the connection passage (86) can continue tocommunicate with the oil groove (80) even when the orbiting scroll (40)moves,

According to this embodiment, in a manner similar to Embodiment 1, abearing oil supply passage (70) is not in communication with the oilgroove (80), a refrigeration oil is caused to flow through the groovecommunication passage (85) only by a pressure difference between an oilreservoir (18) in a casing (15) and the oil groove (80), and a capillarytube (87) forms part of the groove communication passage (85).Accordingly, this embodiment provides advantages similar to those ofEmbodiment 1.

Embodiment 3

Embodiment 3 of the present disclosure will be described below, focusingon differences between a scroll compressor (10) of Embodiment 3 and thatof Embodiment 1.

As illustrated in FIG. 5, in this embodiment, a central cylindricalportion (56) of a lower bearing member (55) is different from that ofEmbodiment 1. Specifically, the central cylindrical portion (56) extendsalong an auxiliary shaft portion (67) which forms a lower end part of adriving shaft (60), from the upper end to the lower end of auxiliaryshaft portion (67). The central cylindrical portion (56) has a recessformed in an upper end part thereof, and a rolling bearing (54) isprovided in the recess. The rolling bearing (54) is penetrated by theauxiliary shaft portion (67) of the driving shaft (60). With thisconfiguration, the central cylindrical portion (56) serves as anauxiliary bearing which supports the auxiliary shaft portion (67).

Further, in this embodiment, a first connection passage (81) formed in afixed scroll (30), a second connection passage (82) formed in a housing(25), a third connection passage (83) formed in the lower bearing member(55), and a connection pipe (84) connecting the second connectionpassage (82) to the third connection passage (83) together form a groovecommunication passage (85).

As illustrated in FIG. 6, the first connection passage (81) located inan outer circumferential portion (33) of a fixed scroll (30), andincludes an inner vertical communicating path (81 a) which verticallyextends in an inner edge part of an outer circumferential portion (33),a transverse communicating path (81 b) which radially extends in theouter circumferential portion (33), and an outer vertical communicatingpath (81 c) which vertically extends in an outer edge part of the outercircumferential portion (33).

The inner vertical communicating path (81 a) has an upper end whichopens on the upper surface of an end plate (31) and a lower end whichopens in an oil groove (80) formed on a thrust sliding surface (35). Theinner vertical communicating path (81 a) has a female thread (81 d)formed on the wall of its upper end part. A rod member (89) which willbe detailed later is provided in the inner vertical communicating path(81 a), and a head (89 d) of the rod member (89) closes the upper end ofthe communicating path (81 a).

The transverse communicating path (81 b) radially outwardly extends froma point located immediately below the female thread (81 d) of the innervertical communicating path (81 a), and has an outer end which opens onthe outer circumferential surface of the fixed scroll (30). The openingof the outer end of the transverse communicating path (81 b) is closedwith a plug member.

The outer vertical communicating path (81 c) extends downwardly from apoint located slightly inward relative to the outer end of thetransverse communicating path (81 b), and has a lower end which opens onthe lower end surface of the fixed scroll (30).

Thus, the inner vertical communicating path (81 a), the transversecommunicating path (81 b), and the outer vertical communicating path (81c) successively communicate with each other, and thereby together formthe first connection passage (81) which connects the oil groove (80) tothe lower end surface of the fixed scroll (30).

The second connection passage (82) vertically extends in an outercircumferential part of the housing (25). An upper end of the secondconnection passage (82) opens on the upper end surface of the housing(25) and corresponds to the outer vertical communicating path (81 c) ofthe first connection passage (81), and thereby causes the secondconnection passage (82) to communicate with the first connection passage(81). On the other hand, a lower end of the second connection passage(82) opens on the lower end surface of the housing (25). The secondconnection passage (82) has a diameter which is slightly larger thanthat of the outer vertical communicating path (81 c) of the firstconnection passage (81). The second connection passage (82) includes, ina lower end part, a smaller diameter section which has a diameterslightly smaller than the diameter of the other part. As will bedetailed later, an upper end part (84 a) of the connection pipe (84) andan upper part (91 b) of a coupling pipe (91) are pressed into thesmaller diameter section. With this configuration, the second connectionpassage (82) connects the first connection passage (81) to theconnection pipe (84).

As illustrated in FIG. 7, the third connection passage (83) includes aninner vertical communicating path (83 a) which vertically extends in thecentral cylindrical portion (56) of the lower bearing member (55), atransverse communicating path (83 b) which radially extends from thecentral cylindrical portion (56) to enter an arm (57), and an outervertical communicating path (83 c) which vertically extends in an outeredge part of the arm (57).

The inner vertical communicating path (83 a) has an upper end which isconnected to the recess and opens below the rolling bearing (54)provided in the recess, and a lower end which opens at the lower end ofthe central cylindrical portion (56) located in an oil reservoir (18).The inner vertical communicating path (83 a) has a female thread (83 d)formed on the wall of its upper end part. Another rod member (89) whichwill be detailed later is provided in the inner vertical communicatingpath (83 a), and the head (89 d) of the rod member (89) closes the upperend of the inner vertical communicating path (83 a).

The transverse communicating path (83 b) radially outwardly extends froma point located immediately below the female thread (83 d) formed in theupper end part of the inner vertical communicating path (83 a), and hasan outer end which opens on the outer circumferential surface of the arm(57). The opening of the outer end of the transverse communicating path(83 b) is closed with a plug member. The outer vertical communicatingpath (83 c) has an upper end which opens on the upper end surface of thearm (57), and a lower end which opens on the lower end surface of thearm (57). The outer vertical communicating path (83 c) communicates withthe transverse communicating path (83 b) at a point located slightlyinward relative to the outer end of the transverse communicating path(83 b).

A lower end part (84 b) of the connection pipe (84) is inserted in anupper part of the outer vertical communicating path (83 c), whose lowerend opening is closed with a plug member. The outer verticalcommunicating path (83 c) has, in its upper end part, a larger diametersection which has a diameter larger than that of a main middle part ofthe communicating path (83 c). In the larger diameter section, the upperhalf has a diameter which is further larger than that of the lower half.A projection (93 a) of a pressing member (93) is inserted in the upperhalf, and an O-ring (92) is provided in the lower half.

The pressing member (93) is a plate-like piece of metal having apenetration hole (93 b) through which the connection pipe (84)penetrates and a bolt hole (93 c) through which a bolt penetrates. Thepressing member (93) has a projection (93 a) which continues from theperipheral wall of the penetration hole (93 b) and projects downwardlyrelative to the other part of the pressing member (93). The pressingmember (93) is fastened to the a (57) of the lower bearing member (55)with the bolt penetrating through the bolt hole (93 c) in such a mannerthat the projection (93 a) penetrates the larger diameter section of theouter vertical communicating path (83 c) while pressing the O-ring (92).The pressing member (93) as described above presses the O-ring (92),through which the connection pipe (84) penetrates, against the outervertical communicating path (83 c). In this manner, sealing between theinner space of the casing (15) and the outer vertical communicating path(83 c) is accomplished.

Thus, the inner vertical communicating path (83 a), the transversecommunicating path (83 b), and the outer vertical communicating path (83c) successively communicate with each other, and thereby together formthe third connection passage (83) which connects the oil reservoir (18)to the connection pipe (84).

The connection pipe (84) is a resin pipe made of a resin material. Asillustrated in FIG. 8, in the connection pipe (84), the upper end part(84 a) has a diameter which is larger than that of a main middle partwhereas the lower end part (84 b) has a diameter which is smaller thanthat of the main middle part. A lower part (91 a) of the coupling pipe(91) which is made of stainless steel is pressed into the upper end part(84 a) having the larger diameter.

In the coupling pipe (91), the lower part (91 a) located lower relativeto the axial midpoint has a diameter which is smaller than that of theupper part (91 b) located upper relative to the axial midpoint.Specifically, the lower part (91 a) of the coupling pipe (91) has anoutside diameter which is slightly larger than an inside diameter of theupper end part (84 a) of the connection pipe (84), and is slightlysmaller than an outside diameter of the upper end part (84 a) of theconnection pipe (84). On the other hand, the upper part (91 b) has anoutside diameter which is substantially equal to the outside diameter ofthe upper end part (84 a) of the connection pipe (84).

As illustrated in FIG. 6, the lower part (91 a) of the coupling pipe(91) is pressed into the upper end part (84 a) of the connection pipe(84), and the upper end part (84 a) is pressed into the smaller diametersection located in the lower end part of the second connection passage(82). Accordingly, the upper end part (84 a) of the connection pipe (84)and the upper part (91 b) of the coupling pipe (91) are in contact withwall of the smaller diameter section in the lower end part of the secondconnection passage (82). Consequently, sealing between the inner spaceof the casing (15) and the second connection passage (82) isaccomplished by the connection pipe (84) and the coupling pipe (91). Inthis manner, the second connection passage (82) communicates with theconnection pipe (84) through the coupling pipe (91) withoutcommunicating with the inner space of the casing (15).

On the other hand, as illustrated in FIG. 7, the lower end part (84 b)of the connection pipe (84) penetrates an upper part of the outervertical communicating path (83 c) of the third connection passage (83).Specifically, the lower end part (84 b) of the connection pipe (84)penetrates through the penetration hole (93 b) of the pressing member(93) and the O-ring (92), and the tip of the connection pipe (84) ispositioned near the point where the outer vertical communicating path(83 c) and the transverse communicating path (83 b) of the thirdconnection passage (83) communicate with each other. This configurationin which the connection pipe (84) penetrates through the O-ring (92) andthen in the outer vertical communicating path (83 c) of the thirdconnection passage (83) allows the third connection passage (83) tocommunicate with the inside of the connection pipe (84) withoutcommunicating with the inner space of the casing (15).

As shown enlarged in FIGS. 6 and 7, each of the rod members (89)provided in the inner vertical communicating path (81 a) of the firstconnection passage (81) and the inner vertical communicating path (83 a)of the third connection passage (83) includes a body part (89 a), asmaller diameter part (89 b), a screw part (89 c), and the head (89 d),all of which are continuously formed from the tip toward the base of therod member.

The body part (89 a) is a rod-like member in a circular column shape andhas a spiral thin groove (89 e) with a width of about 0.5-1.0 mm formedon its outer circumference. The body part (89 a) configured in thismanner causes a narrow spiral channel to be formed between the wall ofeach of the inner vertical communicating paths (81 a, 83 a) and the bodypart (89 a). The smaller diameter part (89 b) has a diameter smallerthan the diameters of the inner vertical communicating paths (81 a, 83a) and causes an annular passage to be formed between the wall of eachof the inner vertical communicating paths (81 a, 83 a) and the smallerdiameter part (89 b). The inner end of each of the transversecommunicating paths (81 b, 83 b) opens in the associated annularpassage. The screw part (89 c) is a rod-like member in a circular columnshape, and has on its outer circumference a male thread which isthreadedly engaged with the female threads (81 d, 83 d) formed in theupper end parts of the inner vertical communicating paths (81 a, 83 a).The head (89 d) is in a disc shape having a diameter larger than thediameters of the inner vertical communicating paths (81 a, 83 a).

The rod member (89) as described above causes, by means of the body part(89 a), the narrow spiral channel be formed in each of the innervertical communicating paths (81 a, 83 a) where the rod member (89) isdisposed. The narrow spiral channel formed on the outer circumference ofthe rod member (89) controls flow rate of the refrigeration oil whichhas flowed into each of the inner vertical communicating paths (81 a, 83a). That is, each of the rod members (89) serves as a throttle forcontrolling the flow rate of the refrigeration oil in the groovecommunication passage (85).

In this embodiment, the groove communication passage (85), whichincludes the first, second, third connection passages (81-83) and theconnection pipe (84), connects the oil groove (80) only to the oilreservoir (18) in the casing (15). Accordingly, in a manner similar toEmbodiment 1, this embodiment is also configured such that an oil supplypassage (77) formed in the driving shaft (60) is not in communicationwith the oil groove (80) formed on the fixed scroll (30). Thus, abearing oil supply passage (70) is not in communication with the oilgroove (80), and the refrigeration oil is caused to flow through thegroove communication passage (85) only by a pressure difference betweenthe oil reservoir (18) in the casing (15) and the oil groove (80).

Specifically, the refrigeration oil in the oil reservoir (8) flowsthrough the groove communication passage (85), by passing consecutivelythrough the third connection passage (83), the connection pipe (84), thesecond connection passage (82), and the first connection passage (81),and then, is supplied to the oil groove (80). Consequently, the oilgroove (80) is filled with the refrigeration oil with a high pressure,and the refrigeration oil in the oil groove (80) gradually flows out toenter a clearance between the thrust sliding surface (45) and the thrustsliding surface (35) to be used to lubricate the thrust sliding surfaces(35, 45).

Thus, also in this embodiment, it is ensured that the refrigeration oilis supplied to the clearance between the thrust sliding surface (45) andthe thrust sliding surface (35). Accordingly, even in a state where theorbiting scroll (40) is strongly pressed against the fixed scroll (30),the friction force generated between the thrust sliding surface (45) andthe thrust sliding surface (35) is not allowed to become excessivelystrong.

Further, the groove communication passage (85) of this embodiment isalso equipped with the throttles, i.e. the rod members (89), forcontrolling the flow rate of the refrigeration oil. Accordingly, also inthis embodiment, even in a state where the orbiting scroll (40) has beentilted and the clearance between the thrust sliding surface (45) and thethrust sliding surface (35) has increased, the flow rate of therefrigeration oil having flowed into the groove communication passage(85) is controlled by the narrow spiral channels formed on the outercircumferences of the rod members (89).

Thus, also in this embodiment, even in a state where the orbiting scroll(40) has been tilted, the flow rate of the refrigeration oil flowingfrom the groove communication passage (85) into the oil groove (80) andthe pressure of the oil groove (80) are kept low. Accordingly, even whenthe orbiting scroll (40) is tilted during operation of the compressionmechanism (20), the pressure acting on the thrust sliding surfaces (35,45) is kept low, and the force separating the orbiting scroll (40) fromthe fixed scroll (30) is not allowed to become excessively strong. Onthe other hand, pressing force acts on the orbiting scroll (40) to pressthe orbiting scroll (40) against the fixed scroll (30). Accordingly, theorbiting scroll (40) which has been tilted during operation of thecompression mechanism (20) quickly restores the original position byreceiving the pressing force. Consequently, this embodiment providesadvantages similar to those of Embodiment 1.

Further, according to this embodiment, the throttle which controls theflow rate of the refrigeration oil in the groove communication passage(85) can be easily provided simply by inserting into the groovecommunication passage (85) the rod member (89) having the spiral groove(89 e) formed on the outer circumference. Furthermore, thecross-sectional area of the groove communication passage (85) can beeasily varied simply by changing the cross-sectional shape of the spiralgroove (89 e) formed on the outer circumference of the rod member (89).That is, use of the rod member (89) as the throttle increases the degreeof freedom of design and makes it easy to change the design.

When using the rod member (89), which has the spiral groove (89 e) onthe outer circumference as described above, as the throttle forcontrolling the flow rate of the refrigeration oil in the groovecommunication passage (85), the narrow channel formed with the spiralgroove (89 e) needs to be long to some extent in order o obtain asufficient throttle effect. Increasing the length of the narrow channelby using a longer rod member (89), however, requires a longer space inwhich the longer rod member (89) is placed. In addition, installation ofthe longer rod member (89) may require much time and effort.

To address this problem, in this embodiment, a plurality of the rodmembers (89) serving as the throttles are provided in a plurality oflocations of the groove communication passage (85). Accordingly, it ispossible to increase the total length of the narrow channels by usingthe rod members (89) each of which is short, and the flow rate of thelubricating oil in the groove communication passage (85) can besufficiently controlled. In other words, providing the plurality of rodmembers (89) in the plurality of locations of the groove communicationpassage (85) makes it possible to reduce the length of each of the rodmembers (89). Consequently, it is unnecessary to ensure long spaces forinstallation of the rod members (89), and the rod members (89) can beeasily installed.

Furthermore, in this embodiment, both of the lower bearing member (55)and the fixed scroll (30) include the connection passages serving as thecommunicating paths which form part of the groove communication passage(85), and are provided with the throttles. Specifically, each of thethird connection passage (83) in the lower bearing member (55) and thefirst connection passage (81) in the fixed scroll (30) is provided withthe rod member (89) serving as the throttle. Accordingly, even if eachof rod members (89) and each of the communicating paths (i.e. the thirdconnection passage (83) and the first connection passage (81)) is short,the narrow channels can have a large length in total. Consequently, theflow rate of the refrigeration oil in the groove communication passage(85) can be sufficiently controlled. In other words, designing each ofthe lower bearing member (55) and the fixed scroll (30) to include theassociated communicating path (i.e. the third connection passage (83) orthe first connection passage (81)) and the associated rod member (89)provided in the associated communicating path enables reduction of thelength of each of the rod members (89). Consequently, it is unnecessaryto ensure long spaces for installation of the rod members (89), and therod members (89) can be easily installed.

According to this embodiment, the connection pipe (84) forming part ofthe groove communication passage (85) is provided between the casing(15) and a motor (50). If the connection pipe (84) provided on a side ofthe motor (50) was a metal pipe, it would be necessary to space theconnection pipe (84) from the motor (50) at a distance which ensuresinsulation, and the diameter of the casing (15) would need to beincreased in accordance with the distance between the connection pipe(84) and the motor (50). In this embodiment, however, the connectionpipe (84) provided on a side of the motor (50) is a resin pipe made of aresin material. Accordingly, it is possible to ensure insulation withoutdistancing the connection pipe (84) from the motor (50). It isconsequently possible to design the casing (15) to have a smallerdiameter, and to downsize the scroll compressor.

The connection pipe (84) may he a metal pipe having only an outercircumferential surface coated with a resin material, instead of thepipe entirely made of a resin material as described above.

Note that the foregoing embodiments have been set forth merely forpurposes of substantially preferred examples, and are not intended tolimit the scope, applications, and use of the present disclosure.

INDUSTRIAL APPLICABILITY

As described above, the present disclosure is useful for the scrollcompressors for compressing, e.g., a refrigerant.

DESCRIPTION OF REFERENCE CHARACTERS

10 Scroll compressor

15 Casing

18 Oil reservoir20 Compression mechanism30 Fixed scroll35 Thrust sliding surface of fixed scroll40 Orbiting scroll41 End plate of orbiting scroll (End plate)45 Thrust sliding surface60 Driving shaft70 Oil supply passage (Bearing oil supply passage)75 Oil supply pump80 Oil groove85 Groove communication passage87 Capillary tube (Throttle)

1. A scroll compressor comprising: a casing; a compression mechanismhoused in the casing, the compression mechanism including a fixed scrolland an orbiting scroll; a driving shaft housed in the casing, the driveshaft being engaged with the orbiting scroll; a bearing oil supplypassage configured to supply the lubricating oil from an oil reservoirlocated in the casing to a bearing location in the compressionmechanism, the bearing location being disposed with the driving shaft;and a groove communication passage, the compression mechanism beingconfigured to discharge a compressed fluid into the casing and togenerate a pressing force pressing the orbiting scroll against the fixedscroll, the orbiting scroll having an end plate with a thrust slidingsurface and the fixed scroll having a thrust sliding surface, the thrustsliding surfaces of the fixed scroll and the orbiting scroll being insliding contact with each other, one of the thrust sliding surfaces ofthe orbiting scroll and the fixed scroll includes an oil groove arrangedsuch that a lubricating oil flows into the oil groove, the bearing oilsupply passage not being in communication with he oil groove, and thegroove communication passage connecting the oil groove to the oilreservoir in the casing.
 2. The scroll compressor of claim 1, whereinthe bearing oil supply passage is provided with an oil supply pumpdriven by the driving shaft and configured to suck the lubricating oilfrom the oil reservoir in the casing and to discharge the lubricatingoil, and the groove communication passage is configured such that thelubricating oil is caused to flow through the groove communicationpassage only by a pressure difference between the oil reservoir and theoil groove.
 3. The scroll compressor of claim 2, wherein the groovecommunication passage is provided with at least one throttle configuredto control a flow rate of the lubricating oil.
 4. The scroll compressorof claim 3, wherein the throttle is at least one rod member disposed inthe groove communication passage, the throttle includes a spiral grooveon an outer circumference, and the spiral groove is configured to allowthe lubricating oil to flow therethrough.
 5. The scroll compressor ofclaim 4, wherein the at least one rod member includes a plurality of rodmembers, and the plurality of rod members are disposed in a plurality oflocations of the groove communication passage.
 6. The scroll compressorof claim 5, further comprising: a bearing separate from the compressionmechanism and supporting the driving shaft in a rotatable manner, thebearing including a first communicating path therein and the fixedscroll including a second communicating path therein, the first andsecond communicating paths forming parts of the groove communicationpassage, and each of the first and second communicating paths beingprovided with an associated one of the rod members.
 7. The scrollcompressor of claim 1, further comprising: a motor configured to driveand rotate the driving shaft; and a connection pipe provided between thecasing and the motor, the connection pipe forming part of the groovecommunication passage, the connection pipe being one of a resin pipemade of a resin material, and a metal pipe having an outercircumferential surface coated with a resin material.
 8. The scrollcompressor of claim 1, wherein a lubricating oil inlet of the groovecommunication passage is located higher than a suction inlet of thebearing oil supply passage.
 9. The scroll compressor of claim 2, furthercomprising: a motor configured to drive and rotate the driving shaft;and a connection pipe provided between the casing and the motor, theconnection pipe forming part of the groove communication passage, theconnection pipe being one of a resin pipe made of a resin material, anda metal pipe having an outer circumferential surface coated with a resinmaterial.
 10. The scroll compressor of claim 2, wherein a lubricatingoil inlet of the groove communication passage is located higher than asuction inlet of the bearing oil supply passage.
 11. The scrollcompressor of claim 3, further comprising: a motor configured to driveand rotate the driving shaft; and a connection pipe provided between thecasing and the motor, the connection pipe forming part of the groovecommunication passage, the connection pipe being one of a resin pipemade of a resin material, and a metal pipe having an outercircumferential surface coated with a resin material.
 12. The scrollcompressor of claim 4, further comprising: a motor configured to driveand rotate the driving shaft; and a connection pipe provided between thecasing and the motor, the connection pipe forming part of the groovecommunication passage, the connection pipe being one of a resin pipemade of a resin material, and a metal pipe having an outercircumferential surface coated with a resin material.
 13. The scrollcompressor of claim 4, wherein a lubricating oil inlet of the groovecommunication passage is located higher than a suction inlet of thebearing oil supply passage.
 14. The scroll compressor of claim 5,further comprising: a motor configured to drive and rotate the drivingshaft; and a connection pipe provided between the casing and the motor,the connection pipe forming part of the groove communication passage,the connection pipe being one of a resin pipe made of a resin material,and a metal pipe having an outer circumferential surface coated with aresin material.
 15. The scroll compressor of claim 5, wherein alubricating oil inlet of the groove communication passage is locatedhigher than a suction inlet of the bearing oil supply passage.
 16. Thescroll compressor of claim 6, further comprising: a motor configured todrive and rotate the driving shaft; and a connection pipe providedbetween the casing and the motor, the connection pipe forming part, ofthe groove communication passage, the connection pipe being one of aresin pipe made of a resin material, and a metal pipe having an outercircumferential surface coated with a resin material.
 17. The scrollcompressor of claim 6, wherein a lubricating oil inlet of the groovecommunication passage is located higher than a suction inlet of thebearing oil supply passage.
 18. The scroll compressor of claim 12,wherein a lubricating oil inlet of the groove communication passage islocated higher than a suction inlet of the bearing oil supply passage.19. The scroll compressor of claim 14, wherein a lubricating oil inletof the groove communication passage is located higher than a suctioninlet of the bearing oil supply passage.
 20. The scroll compressor ofclaim 16, wherein a lubricating oil inlet of the groove communicationpassage is located higher than a suction inlet of the bearing oil supplypassage.